Research glassdoor for potential interview questions for that company
Something else I would recommend would be going online and researching the particular topic you're presenting and seeing if there are any questions on the topic. Reviewing what others have asked and gathering answers will make you more knowledgeable on these topics. If you are concerned with stammering and mixing your words during an interview, I would suggest going online to find popular interview questions. You can also check out Glassdoor, they sometimes provide interview questions for particular companies. What I have found to be the most effective trait to use going into interviews is confidence. Remember, no one knows you better than you; and the interview is based on you! It's always easier to be comfortable when you're the subject matter expert. You have the answers they're looking for, take a deep breath if you get into a pinch, and then put your best response forward.